Radioactive pharmaceuticals are widely used for diagnosis and treatment of certain illnesses such as cancer and heart disease. Frequently these radiopharmaceuticals include a radioactive atom bonded to an organic molecule including, for example, porphyrins, nucleic acids, and enzymes. In order to radio label these organic compounds, relatively pure radioactive atoms or molecules must be isolated.
Rhenium has two useful radioactive isotopes. Rhenium 186 and Rhenium 188. These compounds are formed by irradiating Rhenium metal (as either Rhenium-185 or Rhenium-187) with neutron radiation. For example, in a flux of 10.sup.14 neutrons, cm.sup.-2 s.sup.-1 for 24 hours or more. The formed Rhenium isotope is then transformed into perrhenate by treatment with an oxidizing agent such as hydrogen peroxide or concentrated nitric acid. In the latter case, the solution of perrhenate is then neutralized with a such as ammonia.
Unfortunately, in the oxidation process unwanted by-products are formed which interfere with the successful use of the radioactive perrhenate in forming useful radio labeled organic or inorganic compounds. Accordingly, the perrhenate must be separated from the aqueous crude solution to provide a useful radioactive perrhenate. This is relatively complex since the perrhenate and all the impurities are water soluble and are all in an aqueous solution. Pertechnetate is formed from a Molybdenum-99 generator. Again the pertechnetate is isolated in a relatively crude aqueous mixture and must often be purified before being used to prepare radio labeled organic compounds.